1. Field of the Invention
The present invention relates to an electronic equipment tilting and rotating apparatus, and particularly to a tilting and rotating apparatus for use with a display panel rotating mechanism of a built-in type display apparatus, such as a vehicle television receiver and a car navigation system.
2. Description of the Related Art
As vehicle electronic equipment such as a vehicle television receiver and a car navigation system, there is known built-in type vehicle electronic equipment in which a display apparatus such as a liquid-crystal monitor is housed within a car instrument panel or a car console panel. When this kind of vehicle electronic equipment is not in use, the display apparatus is housed within a compartment portion of a main body of the vehicle electronic equipment. Also, when this vehicle electronic equipment is in use, the display apparatus is moved (slid and tilted) to the ejected position of the front of the main body and it becomes available for practical use.
FIG. 1 of the accompanying drawings shows an example of such vehicle electronic equipment. More specifically, FIG. 1 is an outward appearance perspective view showing the state in which a display panel 91 is moved to the front of a main body 92 of the vehicle electronic equipment and is thereby placed at the ejected position. As schematically shown in FIG. 1, this vehicle electronic equipment comprises the display panel 91, the main body 92 and an arm 93.
As shown in FIG. 1, the display panel 91 is rotatably supported to the main body 92 through the arm 93. Although not shown, the display panel 91 has a suitable means such as a tilt gear disposed at its back surface. This tilt gear is meshed with a transmission gear (that is, part of a mechanical assembly which will be described later on) disposed within the main body 92. Then, the tilt gear is rotated as the transmission gear is rotated, whereby the display panel 91 is rotated around a support shaft 94 of the arm 93.
Although not shown, the main body 92 of this vehicle electronic equipment comprises a compartment portion for housing therein the display panel 91 or the like and a control circuit for energizing and controlling the display panel 91. The main body 92 is held on the vehicle electronic equipment such that the mechanical assembly including the arm 93 can be slid freely.
Although not shown, this mechanical assembly is composed of a sliding and moving mechanism and a tilting and rotating mechanism in addition to the arm 93. The sliding and moving mechanism is composed of a slide motor and a coaxial gear for sliding the mechanical assembly within the main body 92. Also, the tilting and rotating mechanism is composed of a tilt motor and a transmission gear by which the display panel 91 is tilted and rotated.
When the mechanical assembly is slid and moved, the arm 93 moves the display panel 91 while holding the display panel 91 in substantially the horizontal direction. Also, when the display panel 91 is tilted and rotated, the arm 93 properly holds the display panel 91 which can be rotate around the support shaft 94.
Operations of such vehicle electronic equipment according to the related art will be described with reference to FIGS. 2A to 2D. FIGS. 2A to 2D are schematic diagrams to which reference will be made in explaining the manner in which the display panel 91 is slid from the housing position within the main body 92 to the ejected position of the front of the main body 92 so that the display panel 91 may rise from the horizontal state. It is customary that such vehicle electronic equipment is housed within the instrument panel of the car.
First, when the sliding and moving mechanism of the mechanical assembly starts driving the display panel 91 in the state in which the display panel 91 is housed within the main body 92, as shown in FIG. 2A, the display panel 91 joined to the mechanical assembly itself by means of the arm is slid and moved toward the front (shown by an arrow 100A of FIG. 2A) of the main body 92. Then, as shown in FIG. 2B, when the display panel 91 is completely ejected from the main body 92, the sliding and moving mechanism stops driving the display panel 91.
Next, in this state, the tilting and rotating mechanism of the mechanical assembly starts driving the display panel 91. When the tilting and rotating mechanism starts driving the display panel 91, rotation driving force is transmitted to the tilt gear of the display panel 91 so that the display panel 91 is rotated (tilted up) so as to rise in the direction shown by an arrow 110A in FIG. 2C.
After that, the display panel 91 is continued to be tilted and rotated with application of the driving force of the tilting and rotating mechanism and as shown in FIG. 2D, the display panel 91 is tilted up to the available position at which it becomes perpendicular to the arm 93 and at which it becomes available for use, for example. When the display panel 91 is rotated to this position at which it becomes available for use, the tilting and rotating mechanism stops driving the display panel 91.
As described above, according to the related-art vehicle electronic equipment, when a user uses the display panel 91 housed within the main body 92, the display panel 91 can automatically be slid and moved up to the ejected position of the front of the main body 92 so that it can be tilted and rotated up to the available position at which the display panel 91 becomes available for use.
Also, as other driving mechanism for use with vehicle electronic equipment according to the related art, there is known such a driving mechanism by which a display panel can be lowered and moved to properly adjust the available position of the display panel after the display apparatus was slid, moved, tilted and rotated up to the ejected position of the front of the main body when the display apparatus is in use (cited patent reference 1).
[Cited patent reference 1]: Official gazette of Japanese laid-open patent application No. 2003-66855 (page 2, FIG. 4)
However, in the vehicle electronic equipment of the example shown in FIG. 1 and FIGS. 2A to 2D, since the tilting and rotating mechanism starts operating from the state in which the display panel 91 is placed in substantially the horizontal direction shown in FIG. 2B in which the display panel 91 was completely ejected from the main body 92, moment generated by the weight of the display panel 91 is large in the beginning in which the display panel 91 starts rotating so that an initial driving torque becomes is increased unavoidably.
The reason for this will be described below. That is, moment of rotation may be obtained by multiplying a distance (moment's arm) between an action line passing the center of gravity of the display panel 91 and which is generated by the weight of the display panel 91 and the center of the rotary shaft 94 with the weight of the display panel 91. Therefore, the length of the moment's arm is changed with the rotation of the display panel 91. Thus, when the display panel 91 is placed in substantially the horizontal direction, moment of rotation becomes the maximum. When the display panel 91 is placed in the vertical direction, the moment of rotation becomes zero. Accordingly, when the display panel 91 is placed in substantially the horizontal direction, the moment of rotation becomes the maximum value.
Then, the driving torque necessary for rotating the display panel 91 against the moment of rotation generated by the weight of the display panel 91 is increased and hence a motor having a large driving torque becomes necessary. However, when the display panel 91 is tilted and rotated in the state in which the display panel 91 rises to a certain extent, the length of the moment's arm is reduced and hence a driving torque that is not so large is not required. Therefore, when the vehicle electronic equipment is in practical use, it is sufficient that the display panel 91 may be driven with application of a very small driving torque by which “backlash” (play) of a gear and backlash of a driving gear against vibrations of a vehicle can be removed and by which moment of one direction generated around the rotary shaft can be applied to the display panel.
When a motor for tilting and rotating a display panel according to the related art is selected, since a motor corresponding to a large driving torque in the beginning in which the motor starts driving is selected, a motor having a large torque as compared with an average driving torque is selected and there are disadvantages in which the related-art tilting and rotating apparatus consumes large electric power and in which it also occupies a large space.
For these reasons, as a tilting and rotating apparatus for use with vehicle electronic equipment, there has so far been required a tilting and rotating apparatus using a motor having a necessary and minimum driving torque and of which power consumption is small. Also, so far it has been requested that a tilting and rotating apparatus can effectively use a space in the mechanical assembly by using a small motor.